The ordered disintegration of nuclear DNA as a specific genome reaction accompanying apoptosis, stress response and differentiation

V T Solovyan,T Yu Kolotova,I O Andreev,P V Pogrebnoy,D V Tarnavsky

doi:10.7124/bc.000430

Abstract

The treatment of agarose embedded nucleaf or cellular preparations with protein denaturing agents resulted in ordered cleavage of intact nuclear DNA into high molecular weight fragments with the pattern of fragmentation being unityped for various eukaryotic representatives. We showed that the set of DNA fragments represents the pre-existing DNA structural domains attributed to the higher levels of chromatin folding, and presented evidence allowing to interpret the nuclear DNA domain organization as a constituent component of topoisomerase II/DNA complex with its ability to mediate the cleavage/ religation reactions. We demonstrated that changes in the integrity of nuclear D N A , recognizable as an altered pattern of SDS-dependent cleavage of nuclear DNA into high molecular weight DNA fragments, took place at the early stage of apoptosis, upon number of stress challenges and in cells showing various proliferative status. The changes in the integrity of nuclear DNA affected by various influences were shown to be prompt and seem to be of transient nature. The results obtained allow to conclude that changes in the integrity of nuclear DNA revealed as an altered pattern of SDS-dependent high molecular weight DNA cleavage may present the specific genome reaction accompanying the physiological changes in the cells during apoptosis, stress response and differentiation

Highlights

Genomic DNA within eukaryotic cell nucleus appears to be organized into loop domains sized about 40—100 kb, which are fixed on the protein backbone structure referred to as nuclear matrix or chromosome scaffold [1,2,3,4,5,6,7,8,9,10,11]
In the present investigation we report data to show that the changes in the integrity of nuclear DNA accompany various cell programmes including apoptosis, stress response, proliferation and may be interpreted as a specific genome reaction being of physiological value
We showed in our previous works * that the fractionation of agarose embedded nuclei samples, treated with SDS, by field inversion gel electrophoresis (FIGE) results in appearence of two main types of discrete DNA fragments sized about 50—100 kb and 250—300 kb, with the THE ORDERED DISINTEGRATION OF NUCLEAR4 DNA

Summary

Introduction

Genomic DNA within eukaryotic cell nucleus appears to be organized into loop domains sized about 40—100 kb, which are fixed on the protein backbone structure referred to as nuclear matrix or chromosome scaffold [1,2,3,4,5,6,7,8,9,10,11]. In a number of studies using a variety of fractionation techniques both replicating DNA and transcriptionally active sequences were shown to exhibit an altered interaction with nuclear matrix [11, 29,30,31,32,33,34,35] (for review see [19, 33,34,35]) These data indicate that some functionally significant structural rearrangements of chromatin may occur during DNA replication and transcription. It was shown that the formation of discrete set of high molecular weight (HMW) DNA fragments proceeds at the early stages of apoptosis [36, 37 ], which may be interpreted as a key event involved in the programmed cell death [38, 39] This finding suggests that the ordered disintegration of nuclear DNA into HMW-DNA fragments may represent an early event in specific cell programme resulting in cell self-demise. In the present investigation we report data to show that the changes in the integrity of nuclear DNA accompany various cell programmes including apoptosis, stress response, proliferation and may be interpreted as a specific genome reaction being of physiological value

Material and Methods

Results and Discussion

18 Marilley MGassend-Bonnet